fastify vulnerable to request body replacement via an async validation result collision

These records connect through source-stated identifiers. Shared identifiers or dates alone do not establish shared exposure, root cause or applicability.

CVE-2026-84504 · Microsoft / collected KEV context

EUVD-2026-70984

GHSA-667r-xxjv-c9mm

cve-program · CVE-2026-84504

• https://github.com/fastify/fastify/security/advisories/GHSA-667r-xxjv-c9mm
• https://cna.openjsf.org/security-advisories.html

euvd · EUVD-2026-70984

• https://github.com/fastify/fastify/security/advisories/GHSA-667r-xxjv-c9mm
• https://cna.openjsf.org/security-advisories.html

nvd · CVE-2026-84504

• https://cna.openjsf.org/security-advisories.html
• https://github.com/fastify/fastify/security/advisories/GHSA-667r-xxjv-c9mm

osv · GHSA-667r-xxjv-c9mm

• https://github.com/fastify/fastify/security/advisories/GHSA-667r-xxjv-c9mm
• https://nvd.nist.gov/vuln/detail/CVE-2026-84504
• https://github.com/fastify/fastify/commit/f02d8d4ab1ab208f10819c4dc213595b06497833
• https://cna.openjsf.org/security-advisories.html
• https://github.com/fastify/fastify
• https://github.com/fastify/fastify/releases/tag/v5.12.2

• fastify versions before 5.12.2 treat the object resolved by a successful Ajv async validator as the value result protocol used by custom validator compilers. If a request that passes its route schema contains a property named value at the r… · Advisory content revised · 1 Nov 2026